Wireless communication systems, such as wireless local area networks (WLANs), are well known in the art. Generally, such systems comprise transceivers, (i.e., communication stations, (STAs)), which transmit and receive wireless communication signals between each other. Depending upon the type of system, transceivers may take the form of an access point (AP), a wireless transmit/receive unit (WTRU), a node or the like.
FIG. 1 shows a conventional wireless communication system 10 in which an AP 12 provides communication services to a plurality of WTRUs 14. The AP 12 can communicate with a network 18 through an optional access controller (AC) 16, thereby providing additional network services to the WTRUs 14, such as access to the Internet or a public service telephone network (PSTN). Alternatively, the AP 12 can communicate directly with the network 18 without going through the AC 16.
Ideally, all connections within the system 10 should operate at the highest achievable transmission rate in order to maximize performance and overall system capacity. However, it is not always possible to achieve acceptable quality at higher data rates, since they require relatively higher signal-to-noise ratios (SNRs) at the receiver.
This creates a situation where it would be beneficial to adjust the rate at which packets are transmitted, depending on the SNR conditions that are perceived by a transceiver that receives the packet. However, system 10 does not provide a mechanism to transfer perceived channel quality in terms of received signal power, SNR or packet error rate (PER) to the source of the packets. Thus, the basis for decisions for adjusting the transmission rate of the AP 12 and the WTRUs 14 in the system 10 is limited to local transmission conditions.